The present invention relates to a pattern forming method and a pattern forming apparatus for forming patterns of electronic wiring, printed wiring boards, electrodes for semiconductors, electronic devices, display devices, optical devices, signage, ornaments, and the like by using an ink jet method. Particularly, the present invention relates to a pattern forming method and a pattern forming apparatus that can form a pattern having a line width smaller than 100 μm at a high aspect ratio, and relates to an electronic wiring substrate and an optical device formed by the pattern forming method.
In recent years, techniques for forming patterns such as wiring pattern of electronic circuits, electronic wiring patterns on substrates have drawn attention. For forming such patterns, for example, a liquid ejection head for ink jet system (ink jet head) is used. In this case, a liquid in which metal particles or resin particles are dispersed is ejected in the form of droplets from the liquid ejection head (ink jet head) so as to draw a pattern, the droplets are hardened by heating and the like, and thus an electronic wiring pattern is formed.
JP 4575725 B (Patent Literature 1) discloses a method in which a pattern having wettability is formed in modified polyimide according to a desired wiring pattern to be drawn by means of ultraviolet exposure such that the modified polyimide exhibits difference of surface energy, and to the resultant, a conductive ink is ejected in the form of droplets by inkjet so as to form wiring or an electrode.
WO 2009/072603 (Patent Literature 2) describes a pattern drawing method in which an ejection target region in a substrate is irradiated with a laser or infrared so as to preheat the ejection target region, and a liquid is ejected in the form of droplets to the ejection target region by using an ink jet method. According to the method, the liquid droplets that have just ejected to the ejection target region are rapidly solidified, spreading of liquid droplets resulting from wetting of the substrate is inhibited, and at the same time, nozzle clogging is inhibited by the heating of the substrate.